Theta function (disambiguation)

Theta function can refer to

• the Jacobi theta function $\vartheta (z;\tau )$
  • Jacobi theta functions (notational variations) $\vartheta _{ij}(z;\tau ),\vartheta _{j}(z),\theta _{i}(z;q)$
• the q-theta function $\theta (z;q)$
• the Riemann–Siegel theta function $\theta (t)$
• the Ramanujan theta function $f(a,b)$
• Ramanujan's mock theta functions $\mu (q),f(q),\phi (q),\psi (q),\chi (q)$, etc., see Mock modular form
• the Chebyshev function $\vartheta (x)$
• the Riemann theta function $\mathbb {H} _{n}$
• Feferman's function $\theta _{\alpha }(\beta )$, see Ordinal notation
• the E₈ theta function $\Theta _{\Lambda }(\tau )$, see E₈ lattice#Theta function